The delivery of video and other types of content as part of an on-demand service has traditionally been, at least with respect to cable networks, through the use of a VOD server that outputs the requested content as a QAM (Quadrature Amplitude Modulated) signal that is delivered over a cable system to one or more set top boxes. The set top boxes process the signal and supply it to a display device such as a TV set.
Network personal video recorder (NPVR) functionality can be supported by many current VOD servers. NPVR functionality allows a user to use commands of the type normally supported by a video recorder, e.g., fast forward, pause, rewind, etc. The VOD server implements the command or commands and supplies the resulting video stream to the on-demand user.
VOD and NPVR products are two exciting cutting edge products being offered by the cable industry today. However, current VOD servers are primarily designed to work with conventional business management systems and customer premise equipment (CPE), e.g., set top boxes, designed specifically for the cable industry. A business management system may be implemented as a module. In some embodiments the business management systems are implemented as stand alone servers where each server operates as a module in the overall system.
Existing VOD servers used by the cable industry today tend to support standardized protocols explicitly developed for the cable industry with VOD services in mind. The most widely used protocols for VOD services provided by the cable industry are the ISA protocol suite which is part of the Interactive Services Architecture. These protocols are generally referred to as ISA protocols and include a Lightweight Streaming Control Protocol (ISA LSCP), ISA Session Set Up protocol (ISA SSP) and various other ISA protocols. ISA protocols are described at www.interactiveservices.org. Time Warner Cable's Session Setup Protocol (SSP) Version 2.3 dated May 19, 2003 and Lightweight Stream Control Protocol (LSCP) Version 1.1 dated Sep. 5, 2003 which are available at the www.interactiveservices.org website are both hereby expressly incorporated by reference. Additional information on ISA Lightweight service protocols is provided in: 1) the LSCP Implementation Specification Version 1.0 dated Apr. 12, 2004 (TWC-LSCPI-SP-1.0); 2) CableLabs Video-On-Demand Content Specification 1.1 (MD-SP-VOD-CONTENT1.1-I03-040107 dated Jan. 7, 2004 and 3) CableLabs Asset Distribution Interface Specification Version 1.1 (MD-SP-ADI1.1-I03-040107 dated Jan. 7, 2004 each of which is hereby expressly incorporated by reference. A derivative system which uses ISA commands to implement VOD functionality which is also used by many cable companies is the OpenStream system described at www.tandbergtv.com which is an on-demand digital service platform and related protocols that allow cable operators to provide on-demand video services. These cable industry standards are used to provide the backend management functions and interface/APIs for many VOD systems currently in use by the cable industry today. Backend management functions may include such things as, session set up, controlling delivery authorization for users, NPVR functions, and billing functions. Control of delivery may include supporting one or more NPVR features, in response commands received from a CPE device. Thus NPVR may be supported once a stream begins being delivered.
Various video on-demand systems, at least some of which can support network based digital video recorder (network DVR) functionality and which can be used in conjunction with the methods and apparatus of the invention are described in U.S. Patent Application Publications: US 2002-0129358, US 2002-0100059 and US 2002-0104093, which are hereby expressly incorporated by reference.
Existing VOD systems have proven suitable for delivering VOD to typical cable system client devices, e.g., set top boxes. However, recent advances in broadband network used to deliver IP packet streams and IP devices, such as personal computers, personal digital assistants (PDAs), etc. have opened up new opportunities for the delivery of content, e.g., video on-demand.
As video capable IP devices become more numerous, there is an increasing demand for cable companies and other suppliers of content to be capable of delivering video to such non-traditional devices and clients over broadband and wireless connections using IP packet streams. IP devices often rely on Real Time Streaming Protocol (RTSP) signaling to control on-demand streaming. RTSP is a client-server multimedia presentation control protocol, designed to address the need for efficient delivery of streamed multimedia over IP networks. RTSP is described in the Internet Society's Network Working Group Request for Comments (RFC) 2326 dated 1998 which is hereby expressly incorporated by reference. Unfortunately, as discussed above, existing VOD servers used by the cable industry tend to use the ISA protocols as opposed to RTSP to control on-demand services. In addition, many VOD servers in use by the cable industry today to supply VOD content to set top boxes do not support IP packet streaming as a delivery option. Accordingly, much of the VOD equipment currently in use by the cable industry is unable to interact with IP based devices due to protocol difference and due to the failure of many existing VOD servers to support RSTP and/or IP streaming.
One approach to addressing the need to support video delivery to IP clients has been to develop IP business management systems and IP video servers for controlling and delivering video and other content as IP streams to IP client devices, e.g., over a broadband connection which supports IP.
This approach while avoiding the protocol and delivery incompatibility issues has the unfortunate result of requiring duplication of many resources, e.g., servers, content storage, etc. which have already been developed and deployed to support VOD services to non-IP based set top boxes. Such an approach may be suitable for some applications, e.g., IPTV streaming, where the same set of IP video streams are broadcast to a large number of users justifying the cost of new hardware given the number of user's which will benefit from the service. Providing new hardware to support IPTV streaming is, in some respects, easier than implementing new VOD services since the large library of content which may be required to support meaningful VOD services need not be stored and made available on demand.
In view of the above discussion, it should be apparent that it would be desirable if methods and/or apparatus could be developed which would allow existing VOD equipment which supports the ISA protocol and QAM based video delivery normally associated with non-IP set top box VOD systems, to be used to support on-demand content services, e.g., VOD services, for IP client devices such as personal computer based clients and/or IP-video-based STBs. It would be particularly desirable if such methods and apparatus could be used to support RTSP based on-demand services. It would also be desirable if the developed methods could be used to bridge existing non-IP VOD/NPVR systems and IP based systems while still allowing for expansion and flexibility in each of the separate systems over time.